Bzzzzzzzzzzzzzzzzz..
Really tight fit on the Hammond OPTs', I would bet it is your choke thats' making the buzzing sound...it's common for chokes to buzz. Often times builders will rubber mount chokes for this, check the bobbin for looseness on the choke, if so you may have to goop it up with a silicone sealer or some other type stuff to keep it from moving.
____________________________________Rick.............
Bet its' a 60 or 120 Hz buzz!
Really tight fit on the Hammond OPTs', I would bet it is your choke thats' making the buzzing sound...it's common for chokes to buzz. Often times builders will rubber mount chokes for this, check the bobbin for looseness on the choke, if so you may have to goop it up with a silicone sealer or some other type stuff to keep it from moving.
____________________________________Rick.............
Bet its' a 60 or 120 Hz buzz!
Thanks everyone. I took the PCB out and see absolutely nothing wrong. George, I had already taken the rectifier tube out to see if the was a problem. I also checked the SS rectifier diodes to see if there was a low resistance circuit there. Incidentally the choke I am using has 62 ohms of DC resistance. I went for the 'pretty' choke but now I am wondering if that is the problem. I have the 'ugly' choke (Triad C-14X). I'm leaning towards the current choke (Hammond T193H) being the problem. Should I try the ugly choke?
You have a real tight fit between ALL of those transformers and choke. Can you move the choke to the front of the chassis and rotate it 90 degrees? Perhaps you can undo the mounting bolts and just slide it forward to see if the noise goes away. I have that same choke and the edcor transformers on a 10'*12" chassis and have ZERO mechanical noise (and next to no hum at the speakers either).
Did you try it with the Edcor output transformers? Maybe you should.
Have you triple checked all of the components on the circuit board? Have you wired up the simplest mode (triode, no Cathode feedback, no Ultralinear)? Have you got a load on the outputs when you turned it on?
Perhaps you could take a photo of the completed underside of the amp in case you somehow made a mistake with the wiring.
Did you try it with the Edcor output transformers? Maybe you should.
Have you triple checked all of the components on the circuit board? Have you wired up the simplest mode (triode, no Cathode feedback, no Ultralinear)? Have you got a load on the outputs when you turned it on?
Perhaps you could take a photo of the completed underside of the amp in case you somehow made a mistake with the wiring.
Chris,
Thank you for responding. I can do all that you mention since I have not. It makes sense and shame on me for not starting off with the basic hookup. I should know better having experience with mainframe computer upgrades from the old days of wire wraps, overcurrent adjustments etc.
I did not have a load on the speaker outputs. It is kind of cramped. I'm wondering if it would make sense to make another enclosure. I'll try everything you mention. I'll take a photo after Iput it all back together. I removed the PCB to triple check all the components and see if there was any damaged components.
Another question. What was the rating on the fuse that you used?
Thanks so much for responding. I wish I could have got it right from the get-go like you did.
Thank you for responding. I can do all that you mention since I have not. It makes sense and shame on me for not starting off with the basic hookup. I should know better having experience with mainframe computer upgrades from the old days of wire wraps, overcurrent adjustments etc.
I did not have a load on the speaker outputs. It is kind of cramped. I'm wondering if it would make sense to make another enclosure. I'll try everything you mention. I'll take a photo after Iput it all back together. I removed the PCB to triple check all the components and see if there was any damaged components.
Another question. What was the rating on the fuse that you used?
Thanks so much for responding. I wish I could have got it right from the get-go like you did.
G'Day Andy,
Would you believe that I am having VERY similar problems to you? I am building a point to point wiring push-pull amp that is cramped in to a too small chassis with the output transformers mounted directly under the power transformer. I had to modify the output transformer frames a little to get them to fit in the chassis, and it has an oscillation and the output transformers are humming!
Anyway, I am in the middle of a university essay at the moment and don't have the time to trouble shoot it yet.
I am glad I built the SimpleSE first, as it is easy to get a good result and builds the confidence for more involved projects.
I am sure that there will be a simple error that can be fixed. Just need to take a logical and systematic approach.
I started with a very basic setup. As I was using a choke and I did not have a resistor that would fit (for the simple CRC power supply filter), I wired up the power supply with the choke but no external filter cap, no standby switch, no solid state diode switch, no cathode feedback, no ultralinear - just simple triode mode and an on/off switch. I was real cautious of the high voltages, so I triple checked everything. Checked that all of the voltages were correct out of the transformer wires before connecting to the board.
Be careful when making the external connections to the board. When I built mine there were no wiring diagrams on the site to show the under-the-chassis configuration, so I had to mentally flip the board over when working out what went where. Yes it worked straight up, but I was very cautious.
After that I hooked up all of the options.
Interestingly, after a few days it stopped working due to blown fuse. After some investigation I found that the solid state diodes in the power supply had failed short circuit. This may have been from me switching between solid state and tube rectification while the amp was playing. I removed them and the amp runs fine with just tube rectification. I have purchased some higher voltage rated replacements, but have not had the time to put them in yet (and to be honest, I could not hear any difference).
I guess that if your power transformer is 150 mA 750 volts, with 110 volts on the primary you will be drawing just over an amp? So maybe a 2 amp slow blow fuse? (ask one of the experts...)
Hope you get this working soon.
Chris
Would you believe that I am having VERY similar problems to you? I am building a point to point wiring push-pull amp that is cramped in to a too small chassis with the output transformers mounted directly under the power transformer. I had to modify the output transformer frames a little to get them to fit in the chassis, and it has an oscillation and the output transformers are humming!
Anyway, I am in the middle of a university essay at the moment and don't have the time to trouble shoot it yet.
I am glad I built the SimpleSE first, as it is easy to get a good result and builds the confidence for more involved projects.
I am sure that there will be a simple error that can be fixed. Just need to take a logical and systematic approach.
I started with a very basic setup. As I was using a choke and I did not have a resistor that would fit (for the simple CRC power supply filter), I wired up the power supply with the choke but no external filter cap, no standby switch, no solid state diode switch, no cathode feedback, no ultralinear - just simple triode mode and an on/off switch. I was real cautious of the high voltages, so I triple checked everything. Checked that all of the voltages were correct out of the transformer wires before connecting to the board.
Be careful when making the external connections to the board. When I built mine there were no wiring diagrams on the site to show the under-the-chassis configuration, so I had to mentally flip the board over when working out what went where. Yes it worked straight up, but I was very cautious.
After that I hooked up all of the options.
Interestingly, after a few days it stopped working due to blown fuse. After some investigation I found that the solid state diodes in the power supply had failed short circuit. This may have been from me switching between solid state and tube rectification while the amp was playing. I removed them and the amp runs fine with just tube rectification. I have purchased some higher voltage rated replacements, but have not had the time to put them in yet (and to be honest, I could not hear any difference).
I guess that if your power transformer is 150 mA 750 volts, with 110 volts on the primary you will be drawing just over an amp? So maybe a 2 amp slow blow fuse? (ask one of the experts...)
Hope you get this working soon.
Chris
I know it kind of messy now but here is a pic of the underside. I have 8 ohm resistors as a load on the outputs. Still the same 60Hz vibration. Just wanted to share a pic before proceeding with your recommendations Chris.
Also swapped out choke temporarily, had it outside the enclosure on the bench, and I now can confirm that the vibration is coming from the power trans.
Will re-wire to basic config and report my findings.
Also swapped out choke temporarily, had it outside the enclosure on the bench, and I now can confirm that the vibration is coming from the power trans.
Will re-wire to basic config and report my findings.
Attachments
Hard to tell with the photo, but from what I can see, it looks like you have the filament wires, high tension, choke and external capacitor wired up OK. There is just too much going on around the output transformer connections to tell what is happening there. I can see, however, that you have not got it set up for simple triode operation. Try this first. It is just a few wires, and if it works it will tell you where the problem is.
For your input wires it is difficult to tell what you are using. Are they shielded coaxial? if not it looks like you only have one conductor going from your input sockets. Are you running this from a pre-amp or something with a volume control? If you are then you don't need a volume control for the initial set up, but make sure you run the ground wire from the input socket to the board.
If still no joy, can you re-mount the small edcor transformers? If they hum too then you will know it is a problem with your wiring or you placed components on the board incorrectly.
Just noticed also that you have not got a mounting bolt in the middle of the board. You will want to put one there or putting tubes in and out will stress the circuit board.
I normally take the approach that when there is a problem it is something that I have screwed up rather than being a component problem - and I am normally right!
Good luck, it should only take a few minutes to set up for simple triode only operation. Try to keep the wiring neat, it will make it easier for you to see what is going on and easier for others to help too.
And again - Good luck!
Chris
For your input wires it is difficult to tell what you are using. Are they shielded coaxial? if not it looks like you only have one conductor going from your input sockets. Are you running this from a pre-amp or something with a volume control? If you are then you don't need a volume control for the initial set up, but make sure you run the ground wire from the input socket to the board.
If still no joy, can you re-mount the small edcor transformers? If they hum too then you will know it is a problem with your wiring or you placed components on the board incorrectly.
Just noticed also that you have not got a mounting bolt in the middle of the board. You will want to put one there or putting tubes in and out will stress the circuit board.
I normally take the approach that when there is a problem it is something that I have screwed up rather than being a component problem - and I am normally right!
Good luck, it should only take a few minutes to set up for simple triode only operation. Try to keep the wiring neat, it will make it easier for you to see what is going on and easier for others to help too.
And again - Good luck!
Chris
Thanks Chris. I do intend to take all your steps but want to report this finding:
I have the simplest wiring in place, the basic triode setup. I even took the PS filter cap out of the circuit. I still get that vibration with the high voltage (red) wires attached. If I remove them, it runs quiet, and all the tube filaments glow a nice normal red color. I'm using shielded coax for the inputs. Have not hooked up pot yet. I have the input grounded.
I thought I might be getting feedback because the input jacks are so close to the opt secondary but the power trans still vibrates will all the tubes unplugged. I'm going continue with your recommendations.
Thanks.
I have the simplest wiring in place, the basic triode setup. I even took the PS filter cap out of the circuit. I still get that vibration with the high voltage (red) wires attached. If I remove them, it runs quiet, and all the tube filaments glow a nice normal red color. I'm using shielded coax for the inputs. Have not hooked up pot yet. I have the input grounded.
I thought I might be getting feedback because the input jacks are so close to the opt secondary but the power trans still vibrates will all the tubes unplugged. I'm going continue with your recommendations.
Thanks.
Sorry I can't be more help, I am definitely a beginner in this field!
Is it easy to put the small edcors back on the chassis? It might be worth trying that. Otherwise I am out of suggestions.
Make sure you get the wiring righ t for the transformer. Use the schematic tab from this page.
http://www.edcorusa.com/products/transformers/xse/xse15-8-5k.html
Compare to the wiring of the hammond here http://www.hammondmfg.com/1627.htm
Make sure you compare to the schematic on the Tubelab site, just to make sure it is right too
http://www.tubelab.com/AssemblyManualSimpleSE/schematic_SSE.htm
The more knowledgeable members might have some more help.
Chris
Is it easy to put the small edcors back on the chassis? It might be worth trying that. Otherwise I am out of suggestions.
Make sure you get the wiring righ t for the transformer. Use the schematic tab from this page.
http://www.edcorusa.com/products/transformers/xse/xse15-8-5k.html
Compare to the wiring of the hammond here http://www.hammondmfg.com/1627.htm
Make sure you compare to the schematic on the Tubelab site, just to make sure it is right too
http://www.tubelab.com/AssemblyManualSimpleSE/schematic_SSE.htm
The more knowledgeable members might have some more help.
Chris
I have the Allied 6K7VG.
I started to trace out from the high voltage secondary to see where there may be a problem and I noticed one of the SS rectifiers (FRED) measures 338 ohms and the other measures about 50k ohms. Both were measured paying attention to the polarity of the leads. (Negative on cathode side of tube rectifier.) That seems strange. Maybe I should remove them since I am using the GZ34?
I started to trace out from the high voltage secondary to see where there may be a problem and I noticed one of the SS rectifiers (FRED) measures 338 ohms and the other measures about 50k ohms. Both were measured paying attention to the polarity of the leads. (Negative on cathode side of tube rectifier.) That seems strange. Maybe I should remove them since I am using the GZ34?
I have limited access to this forum at work, so I must be brief. I use a 2 amp slow blow fuse in my amps. I know for a fact that it will instantly blow if there is a short in the HV wiring. Try a 2 amp fuse, if it blows quickly there is a short. Continued operation with a larger fuse will result in a toasted transformer. Testing for a few seconds (2 or 3) at a time should be OK.
I have used the Allied transformers for years and never had one buzz loudly. A loud buzz is usually the sign of a severe overload on the transformer.
This sounds like a shorted diode. If you have SS rectifiers in your amp check them with an ohmeter to see if one has shorted out. I also had one fail shorted, and it did happen when I flipped the rectifier switch with the power on. It instantly took out the 2 amp fuse. Perhaps the cheap IXYS Fred diodes are not up to this task, however the replacment (IXYS) diodes have been in the amp for almost a year, and I still flip the switch with the power on. I have seen diodes that test OK with an ohmeter, but break down under high voltage. If unsure, remove the diodes until this is sorted out.
If it still buzzes, disconnect the OPT's (one at a time). If it still buzzes, disconect the choke. If it still buzzes there isn't much left in the circuit but the diodes and C1. Make sure that C1 and C2 are facing the proper direction. The negative stripes should be toward each other.
A 62 ohm choke is not an issue. I have operated my amp with a jumper wire in place of the choke. This was done to see how much power I could squeeze out of this amp. There was a slight hum from the speaker, but none from the transformer. I have even connected an 800 VCT transformer up with the choke jumpered. I got 530 volts of B+ on the SS rectifiers, which is far too much for the 500 volt caps, but I believe in testing things at extremes beyond normal operation to find weak links before I turn them loose on the world.
If this doesn't help, attach a DC voltmeter across the B+ (where the suplemental cap used to be) and then power up the amp. The voltage should settle out to about 430 volts (higher without a load). If it doesn't you have a power supply problem.
I have used the Allied transformers for years and never had one buzz loudly. A loud buzz is usually the sign of a severe overload on the transformer.
This sounds like a shorted diode. If you have SS rectifiers in your amp check them with an ohmeter to see if one has shorted out. I also had one fail shorted, and it did happen when I flipped the rectifier switch with the power on. It instantly took out the 2 amp fuse. Perhaps the cheap IXYS Fred diodes are not up to this task, however the replacment (IXYS) diodes have been in the amp for almost a year, and I still flip the switch with the power on. I have seen diodes that test OK with an ohmeter, but break down under high voltage. If unsure, remove the diodes until this is sorted out.
If it still buzzes, disconnect the OPT's (one at a time). If it still buzzes, disconect the choke. If it still buzzes there isn't much left in the circuit but the diodes and C1. Make sure that C1 and C2 are facing the proper direction. The negative stripes should be toward each other.
A 62 ohm choke is not an issue. I have operated my amp with a jumper wire in place of the choke. This was done to see how much power I could squeeze out of this amp. There was a slight hum from the speaker, but none from the transformer. I have even connected an 800 VCT transformer up with the choke jumpered. I got 530 volts of B+ on the SS rectifiers, which is far too much for the 500 volt caps, but I believe in testing things at extremes beyond normal operation to find weak links before I turn them loose on the world.
If this doesn't help, attach a DC voltmeter across the B+ (where the suplemental cap used to be) and then power up the amp. The voltage should settle out to about 430 volts (higher without a load). If it doesn't you have a power supply problem.
Ha Ha Ha!
While you were taking yours out, I was putting mine IN!!!
You sparked my curiosity about the voltages, so I put mine on its side, took the bottom off and measured some voltages. I was getting about 820 unloaded out of the transformer, 780 loaded (I think?). Getting 480 across the external motor run cap.
Anyway, the interesting thing, when I put the amp right way up and turned it on, there was a fireworks display inside the rectifier tube for a few seconds, then the fuse blew. Did a check, looked like when I had the unit on its side, I had strained one of my input cables so that the exterior insulation had split exposing the coax shield. Looked to se if I could see any obvious shorts - nope. Replaced fuse and same thing happened! Figured I had blown the tube, so opened it up again and soldered in the diodes.
Turned it on, when I turned on the standby switch I heard a mechanical hum/chirp for about a second. This was a similar (but much louder) sound to what I heard just before the fuse would blow when the solid state diodes failed short circuit last time. I quickly turned the amp off. Checked the fuse - it was OK. Turned the amp on again - silent. Checked the voltages - getting correct DC. Hooked it up - now working OK.
Hmmmmm. Don't know what happened. Maybe a loose bit of junk had shorted somewhere when I had the amp on its side?
Now, my question. I don't want to keep frying fuses (I don't have many left), so I am reluctant to stick the rectifier tube back in if it is wrecked. Is the rectifier tube damaged if there was arcing going on inside? I think I read somewhere that when this happens tracks are burned in the internal insulation, rendering it useless.
Also, I had a GZ34 in there and as fate may have it, I ordered a couple of 5U4G tubes for a future project. I see on the SimpleSE page that George has tried a 5U4G, so I am guessing that I can plug one of these in...
Anyway, most importantly, have you got music out of it yet Andy?
Hope it is working for you.
Looks like the solid state rectification has been problematic for a few of us. Can't remember exactly what diodes I put back in, but they were a 220 package, and I think they were a 1500 volt damper diode...
Cheers!
While you were taking yours out, I was putting mine IN!!!
You sparked my curiosity about the voltages, so I put mine on its side, took the bottom off and measured some voltages. I was getting about 820 unloaded out of the transformer, 780 loaded (I think?). Getting 480 across the external motor run cap.
Anyway, the interesting thing, when I put the amp right way up and turned it on, there was a fireworks display inside the rectifier tube for a few seconds, then the fuse blew. Did a check, looked like when I had the unit on its side, I had strained one of my input cables so that the exterior insulation had split exposing the coax shield. Looked to se if I could see any obvious shorts - nope. Replaced fuse and same thing happened! Figured I had blown the tube, so opened it up again and soldered in the diodes.
Turned it on, when I turned on the standby switch I heard a mechanical hum/chirp for about a second. This was a similar (but much louder) sound to what I heard just before the fuse would blow when the solid state diodes failed short circuit last time. I quickly turned the amp off. Checked the fuse - it was OK. Turned the amp on again - silent. Checked the voltages - getting correct DC. Hooked it up - now working OK.
Hmmmmm. Don't know what happened. Maybe a loose bit of junk had shorted somewhere when I had the amp on its side?
Now, my question. I don't want to keep frying fuses (I don't have many left), so I am reluctant to stick the rectifier tube back in if it is wrecked. Is the rectifier tube damaged if there was arcing going on inside? I think I read somewhere that when this happens tracks are burned in the internal insulation, rendering it useless.
Also, I had a GZ34 in there and as fate may have it, I ordered a couple of 5U4G tubes for a future project. I see on the SimpleSE page that George has tried a 5U4G, so I am guessing that I can plug one of these in...
Anyway, most importantly, have you got music out of it yet Andy?
Hope it is working for you.
Looks like the solid state rectification has been problematic for a few of us. Can't remember exactly what diodes I put back in, but they were a 220 package, and I think they were a 1500 volt damper diode...
Cheers!
Oh no! Chris, I hope I wasn't indirectly responsible for your grief. Glad to hear you got it running. I just took a ride out to get fuses and I could have sworn they were the/a standard size. They don't fit in the receptacle. They are ceramic case. Now I have to go 20 minutes each way to get different size. Haven't hooked it to speakers yet. I have a pair of the Fostex FE208E Sigma BLH enclosures with the FE207E in my garage. I'll let you know how it sounds.
As for your rectifier tube, I really don't know enough to answer.
Later
Andy
As for your rectifier tube, I really don't know enough to answer.
Later
Andy
A rectifier that arced over may still work OK. The arcing may burn off some of the cathode coating rendering that particular area of the cathode dead. Fortunately there is plenty of reserve area in most tubes. In some rare cases a chunk of the coating may get wedged between the cathode and the plate making another arc more likely.
I have an RCA 5AR4 in my TubelabSE that is operating with a 100uF input cap. Max spec is 40uF. It arcs every once in a while on power up, but then functions normally. It has done that for about 3 years now, and it still works fine. Unfortunately I was poking around inside that amp when the fireworks happened, and it is now dead. I have not had time to fix it. I, however have several other amps.
A 5U4 will work, but it has a higher internal voltage drop so you will get less high voltage. It also draws 3 amps of filament current to help keep your power transformer warm at night.
It is alive in basic triode mode. It sounds alot better than the Kenwood SS receiver I was using already. Currently using the EL34's. I cannot hear any hum at all Anyway, I'm going to install the volume control and switch it over to UL w/ CFB. (Was using XM as input with line level at min.) I will probably plug in the KT88's to accentuate the bass a little.
Thanks for all the help Chris and Tubelab.
Thanks for all the help Chris and Tubelab.
Finished up. Installed volume control, converted to UL w/ CFB. Cleaned up wires. Installed KT88s. Powered up and cannot not hear any hum. Only very slightly with my ear up against FE207E. Turned up volume and it sounds wonderful. I guess I should let it run for a while?
Thanks everyone especially Tubelab and Chris for your help with this.
Here it is fired up on my workbench (See attached.)
Thanks everyone especially Tubelab and Chris for your help with this.
Here it is fired up on my workbench (See attached.)
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